Bendable base insulator



Aug. 2, 1966 c. m. HERO BENDABLE BASE INSULATOR Filed Nov. 20, 1964 FIG5 INVENTOR.

CARL D. FIERO ATTORNF'YS United States Patent York Filed Nov. 20, 1964,Ser. No. 412,699 Claims. (Cl. 174-158) The present invention relates toa bendable support or base for electric insulators and more particularlyto a bendable support or base member adapted to be interposed betweenthe ceramic body of an electric insulator and the pole, tower or otherstructure supporting the insulator, such member being arranged so as tobe bendable laterally in the direction of the line conductor that issupported by the insulator. Such bending allows the insulator to cant inresponse to overload transverse stress placed upon the insulator by theconductor, for example, from a break in the conductor on one side of theinsulator.

Previous station and line post insulators have been mounted rigidlyrelative to their supporting structures. They have ordinarily extendedeither vertically or generally horizontally from poles or towers so thatstresses placed on them by the supported line conductor were transverseto the insulators and operated in cantilever. Also, power lineinsulators are preferably made of frangible ceramic material that is nothighly resistant to transverse or cantilever stresses.

The stringing tension of the line conductor supported by line postinsulators is frequently 5000 to 6000 pounds and often exceeds thecantilever strength of the insulators which support it, so that when theline breaks, the transverse stress from the tension of the unbrokenspans suddenly appears on the insulators next to the break and is oftensufficient to break them. Breakage of these insulators in turn lets theline conductor down and can place succeeding insulators under overloadcantilever stress whereby the insulator breakage is cascaded down theline. Any such insulator breakage lets the line down and increases thedanger, ditficulty, time, and expense of repair.

It is an object of this invention to prevent breakage of insulators inresponse to transverse stresses produced by conductor breakage.

Another object of the invention is to prevent cascading insulatorbreakage in response to a break in a line conductor.

Another object of the invention is to reduce the cost and complexity ofrepairing a broken line conductor.

Another object of the invention is to minimize the danger and damagefrom the breaking of a line conductor.

Another object of the invention is to make replaceable bendable basesthat are adapted to relieve insulators of overload transverse stressesespecially from a break in a power line. I

Another object of the invention is to make insulator bases that arerelatively rigid vertically or in directions transverse to the lineconductor supported by the insulator and that are bendable in thedirection of the line conductor to relieve the insulators of overloadtransverse stresses resulting from a break in the line.

To these and other ends the invention resides in certain improvementsand combinations, all as will be hereinafter more fully described, thenovel features being pointed out in the claims at the end of thisspecification.

In the drawings:

FIG. 1 shows a plan view of a horizontally mounted line post insulatorsupporting a line conductor and having a bendable base according to theinvention;

FIG. 2 shows a side elevation of the insulator of FIG. 1;

FIG. 3 shows a partial top view of the insulator of FIG. 1 with its basebent;

p 3,264,405 Patented August 2, 1966 ice FIG. 4 shows a plan view of abendable base for an insulator according to the invention; and

FIG. 5 shows a side elevation of a standard line post insulator having abendable base that is bent.

The drawings illustrate the invention as applied to standard line postinsulators and horizontal mounting line post insulators. The inventioncan also be used with station posts, cap and pin insulators, and anyinsulator that is rigidly mounted so as to be subjected to transverse orcantilever stresses. FIGS. 1-3 show a horizontal mounting line postinsulator 10 arranged on a supporting structure 11 such as aconventional pole or tower. A conductor 13 is supported at the outer endof insulator 10 in a conventional manner.

A bendable material such as steel preferably in the form of web 14 isarranged between the ceramic body of the insulator 10 and the supportstructure 11. Web 14 is oriented transversely of conductor 13 so as togive relatively rigid vertical support to insulator 10 and conductor 13and to be bendable only laterally of support structure 11 andlongitudinally of conductor 13.

Bendable web 14 is preferably cast, welded, or otherwise forrnedintegrally with plates 16 and 17plate 16 being adapted for attachment tosupporting structure 11, and plate 17 being either integral with base 15of insulator 10 or adapted for attachment to base 15. As illustrated inFIGS. 13, plate 17 is bolted to base 15 of insulator 10, and plate 16 isbolted to support structure 11. When a bendable base including bendableweb 14 is formed integrally with the insulator base 15, the entire base,including bendable web 14, is cemented to the ceramic body of insulator10 in the usual fashion.

FIG. 3 illustrates bendable web 14 as bent in response to overloadtransverse stress placed upon insulator 10 by the line conductor. When abreak in the line occurs on one side of insulator 10, insulator 10 isheavily stressed from the other side by both the tension and weight ofthe next unbroken span of conductor, and such stress tends to cantinsulator 10. Bending of bendable web 14 allows insulator 10 to cant andintroduces slack into the intact span of line, thus greatly reducingline tension between insulator upholding the intact span so as to reducethe transverse stress on insulator 10 produced by the break in the line.

Although canting of insulator 10 may shorten the distance spanned by theintact conductor by only a few inches, such efiFective shorteninggreatly reduces the tension in that span. It is preferred that insulator10 is made strong enough to withstand the transverse stress remainingafter it has canted to introduce tension-relieving sag in the intactspan. Thus, bendable web 14 operates to limit the transverse stress onfrangible, ceramic insulator 10 to values below those capable ofbreaking the insulator.

As best seen in FIG. 2, bendable web 14 has great strength and rigidityvertically of conductor 13 and can uphold insulator 10 against theweight of the conductor 13. Bendable web 14 is preferably made of athickness and strength such that it will bend before the transversestresses on insulator 10 exceed its breaking point. Also, the relativestrength of insulator 10 and the yield strength of bendable web 14, arepreferably selected relative to the transverse stress expected to beplaced upon insulator 10 by a break in conductor 13 so that the bendingof the bendable web 14 will cant insulator 10 to reduce line tensionsufficiently so that insulator 10 will withstand the remainingtransverse stress and not break. In turn, if insulator 10, because ofbendable web 14, is able to withstand the stress of a line breakagewithout failing, cascading insulator breakage is avoided.

FIGS. 4 and 5 show a bendable web insulator base adapted for a standardline post insulator. This base has a pair of cooperating bendable webportions 20 arranged diametrically on opposite sides of a centralaperture 21 in plates 18 and 19. Aperture 21 is arranged for receiving amounting stud by which insulator 22 is connected to pole 11 in the usualfashion. With such an arrangement, the mounting stud (not shown) bendsalong with bendable web portions 20. The illustrated bendable baseincluding bendable webs 20 and plates 18 and 19 is adapted for eitherconnection to or integration with the base of an insulator, and althoughplates 18 and 19 are illustrated as circular, they can be square,rectangular, or any other convenient shape.

In FIG. bendable web 20 is shown as bent in response to the transversecantilever stress placed upon insulator 22 by the intact span ofconductor 23. This bending allows insulator 22 to cant in the directionof the intact span of conductor 23, and this reduces the transversestress on insulator 22 so as to prevent its breaking.

Bendable webs incorporated in insulator bases according to the inventionnot only relieve insulators of breakage and prevent cascading insulatorbreakage, but keep unbroken spans of line conductor aloft and secure tounbroken insulators and supporting structures so as to reduce the shockhazards and danger from line conductor breakage. This saving ofinsulators from breakage in response to line conductor breakage alsosimplifies repairs. In some instances it is possible to splice thebroken line and leave the insulators with bent bases in place andoperating. Bent-base insulators can then be replaced later at theconvenience of the line crew. This speeds repairs to broken lineconductors by eliminating the necessity for immediate replacement ofbroken insulators. Depending upon the construction of the insulator andthe bendable web base portion, either the bendable base portion only, orthe insulator having an integral bendable base can be replaced. Also, itis possible to repair bent insulator bases by bending them back to theiroriginal positions with or without disconnecting the line from theinsulator.

While the invention has been disclosed herein by reference to thedetails of a preferred embodiment, it is to be understood that suchdisclosure is intended in an illustrative, rather than a limiting sense,and it is contemplated that various modifications of the constructionand arrangement of the parts will readily occur to those skilled in theart, within the spirit of the invention and the scope of the appendedclaims.

I claim:

1. An insulator for attaching line conductor means which include a lineconductor, to a support structure, said 5 insulator comprising: adielectric body having a distal end and a proximal end; holding means atsaid distal end for holding said line conductor means with thelongitudinal axis of said conductor when in position being coincident atsaid holding means with a straight reference line; base means at saidproximal end, which comprise inelastic web means that support said bodyand that are unyieldingly rigid relative to stress components at leastup to the weight of said body and line conductor means including saidline conductor, when applied to said web means transversely to saidreference line, but bendingly yieldable to stress components sufficientto break said body when applied along said reference line to said distalend, whereby, when line conductor means including a line conductor areheld by said insulator and stress components sufiicient to break saidbody are applied through said line conductor, said insulator is cantedto relieve at least a portion of said stress component.

2. An insulator according to claim 1, wherein said web means comprise asingle, inelastic web, the dimension of which transverse to said lineand to its dimension from the body end of the web to the supportstructure end of the web is substantially greater than its dimensiongenerally parallel to said line.

3. An insulator according to claim 1, wherein said web means comprise aplurality of inelastic Webs, the dimensions of which transverse to saidline and to their dimensions from the body end of the web to the supportstructure end of the web are substantially greater than their dimensionsgenerally parallel to said line.

4. An insulator according to claim 1, wherein said web means are steel.

5. An insulator according to claim 1, wherein said base means includesmeans for securing said body to said web means and means for fasteningsaid web means to said support structure.

References Cited by the Examiner OTHER REFERENCES Electrical World, vol.156, No. 19, Nov. 8 and 9.

LARAMIE E. ASKIN, Primary Examiner.

1. AN INSULATOR FOR ATTACHING LINE CONDUCTOR MEANS WHICH INCLUDE A LINECONDUCTOR, TO A SUPPORT STRUCTURE, SAID INSULATOR COMPRISING: ADIELECTRIC BODY HAVING A DISTAL END AND A PROXIMAL END; HOLDING MEANS ATSAID DISTAL END FOR HOLDING SAID LINE CONDUCTOR MEANS WITH THELONGITUDINAL AXIS OF SAID CONDUCTOR WHEN IN POSITION BEING COINCIDENT ATSAID HOLDING MEANS WITH A STRAIGHT REFERENCE LINE; BASE MEANS AT SAIDPROXIMAL END, WHICH COMPRISES INELASTIC WEB MEANS THAT SUPPORT SAID BODYAND THAT ARE UNYIELDINGLY RIGID RELATIVE TO STRESS COMPONENTS AT LEASTUP TO THE WEIGHT OF SAID BODY AND LINE CONDUCTOR MEANS INCLUDING SAIDLINE CONDUCTOR, WHEN APPLIED TO SAID WEB MEANS TRANSVERSELY TO SAIDREFERENCE LINE, BUT BENDINGLY YIELDABLE TO STRESS COMPONENTS SUFFICIENTTO BREAK SAID BODY WHEN APPLIED ALONG SAID REFERENCE LINE TO SAID DISTALEND, WHEREBY, WHEN LINE CONDUCTOR MEANS INCLUDING A LINE CONDUCTOR AREHELD BY SAID INSULATOR AND STRESS COMPONENTS SUFFICIENT TO BREAK SAIDBODY ARE APPLIED THROUGH SAID LINE CONDUCTOR, SAID INSULATOR IS CANTEDTO RELIEVE AT LEAST A PORTION OF SAID STRESS COMPONENT.